Indonesian workers pack ballot papers as they print it for the upcoming presidential elections in Jakarta, Indonesia, on June 14.

European Pressphoto Agency

JAKARTA, Indonesia—Tonight’s presidential debate in Indonesia will focus in on a pressing question: how to inject new life into Southeast Asia’s largest economy.

Front-runner Joko Widodo, governor of Jakarta, and Prabowo Subianto, a former army general, have broadly similar economic platforms, and tonight will be a chance to show how they plan to achieve their goals and where they differ on the details.

Indonesia’s economic growth in 2013 fell below 6% for the first time since 2009, while the rupiah was the worst-performing currency in the region, sliding more than 20% against the U.S. dollar.

Some of that is due to global events, but investors and economists also point to policy uncertainty, a lack of economic reform, and the age-old problem of graft in the trillion-dollar economy.

So far, both Mr. Widodo and Mr. Subianto have spoken in general terms about the need to increase food and energy security, to cut costly fuel subsidies that have put pressure on a rising budget deficit, and to invest billions of new dollars in long-overdue infrastructure projects.

One of most pressing problems facing either president will be reigning in the nation’s spending on fuel subsidies, which has exploded in recent years due to increased consumption by a rapidly expanding middle class. The country of almost 250 million people spends about $12 a day for every driver, leaving it with little leftover to build the seaports, airports, roads and other infrastructure that its businesses need to overcome worsening bottlenecks.

Both Mr. Widodo and Mr. Subianto have said they will cut subsidies—a politically difficult move that meets resistance from the millions who say they will suffer– but the details of such plans are pending.

They both also say they’ll push huge new investments in infrastructure, and analysts will be watching for clear signs of how they’ll do it.

Hashim Djojohadikusumo, Mr. Subianto’s younger brother, one of the country’s richest businessmen and a senior politician in his Gerindra Party, said in a recent forum that Mr. Subianto would raise hundreds of billions by doubling the country’s debt, which as a percentage of GDP is among the lowest in the world.

He also said Mr. Subianto believes growth rates are too low, suggesting that 9-10% growth will be necessary in the coming decades to account for population growth.

Mr. Widodo’s campaign team has suggested current growth rates are sufficient.

Nationalist rhetoric is likely to figure into many answers, with both men calling for greater self-reliance in energy and agriculture. They will also likely stress a common refrain among Indonesian politicians about the need to add value to the major elements of Indonesia’s economy – such as minerals – to avoid falling into a “resource trap.”

The other aspect of the debate is a focus on welfare, and here too both men are likely to talk about reducing poverty, closing the equality gap and raising the living standards of tens of millions of farmers, whose electoral support will be key to clinching the July vote.

About Southeast Asia Real Time

Indonesia Real Time provides analysis and insight into the region, which includes Singapore, Thailand, Indonesia, Vietnam, Malaysia, the Philippines, Myanmar, Cambodia, Laos and Brunei. Contact the editors at SEAsia@wsj.com.

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